Exterior shell of an aerodynamic highway tractor



FIG. 1 is a front and left side perspective view of an exterior shell of an aerodynamic highway tractor showing my new design, it being understood that the broken lines are for illustrative purposes only and form no part of the claimed design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a left side elevation view thereof, the right side being a mirror image of that shown; and

FIG. 4 is a top plan view thereof. 

The ornamental design for an exterior shell of an aerodynamic highway tractor, as shown and described. 